The present invention relates to radiation shielded carriers for integrated circuit packages.
Electrons trapped in high earth orbits and electrons and protons trapped in low and medium earth orbits cause a high level of ionizing radiation in space. Such ionizing radiation causes an accumulation of charge in electronic circuits which eventually results in a malfunction or failure of the circuits.
Shielding is commonly provided to protect radiation sensitive components. Currently, flat slabs of high-Z metal or layers of high-Z and low-Z metals are attached to either the top or top and bottom of electronics packages for shielding. The high Z metals, such as tungsten/copper alloys, absorb ionizing radiation, such as protons and electrons, and reemit the energy from such radiation in the more innocuous forms of light, some heat, and secondary electrons. Secondary electrons have a very short range and are mostly absorbed by high Z metals, as well. The low Z materials, such as aluminum, also absorb secondary electrons, and can improve the efficiency of the shield. However, such configurations do not protect sensitive electronics from radiation entering from the sides of the device, where no shielding material is present.
Shielding material is also used to encapsulate the integrated circuit die. Connections are provided within the shield from the integrated circuit die to package leads extending out of the shielding material. The shield encapsulating the integrated circuit die must be vertically sealed. See, example, U.S. Pat. No. 5,635,754. While usually providing better radiation protection, such devices are complex and expensive to manufacture.
Another method for protecting sensitive electronics is to design a radiation tolerant integrated circuit die that can withstand high levels of ionizing radiation. These design methodologies can involve redundancy of electronic circuits, suitable doping of the semiconductor material, and spacing of electronic circuits. These methodologies are not normally used in commercially available electronics and require increased cost for redesign and production.
According to the present invention, a radiation shielded carrier is provided for protecting an integrated circuit package from ionizing radiation, which completely encapsulates the integrated circuit package.
In one embodiment of the present invention, a radiation shielding system for protecting an integrated circuit package from ionizing radiation is provided for an integrated circuit package which is substantially planar and has a plurality of package leads extending from at least one surface of the package, substantially perpendicular to a surface of the integrated circuit package. The system comprises a base portion comprising shielding material and defining a well for receiving the integrated circuit package. A lid of shielding material is provided for being attached to the base portion to completely encompass the integrated circuit package. The system also includes means for allowing portions of each of the package leads to exit the well when the integrated circuit package is within the well. The means includes insulating material.
In another embodiment of the invention, a radiation shielded integrated circuit device comprises an integrated circuit package including an integrated circuit die electrically connected to a plurality of package leads. Shielding material completely encompasses the integrated circuit package. The shielding material defines a plurality of openings. The number of openings is at least equal to the number of leads of the integrated circuit package and the locations of the openings correspond to the locations of each of the package leads such that each package lead extends through a respective opening in the shielding material. Insulating material is provided in the openings.
In accordance with another embodiment of the invention, a radiation shielded integrated circuit device comprises an integrated circuit package including first and second substantially planar surfaces and two rows of package leads extending from opposing edges of the first surface, substantially parallel to the first surface. Each row extends in opposite directions. Shielding material is provided including first and second substantially planar surfaces opposing the first and second surfaces of the integrated circuit die, respectively. Four side walls of shielding material connect the first and second planar surfaces of shielding material. Insulating material is disposed along two opposing side walls of shielding material. The insulating material defines a plurality of openings corresponding to the number and location of the package leads. Each of the package leads extends through a respective opening.